The present invention relates to a steam generator system, for use as a steam cleaning machine, particularly in the automotive field, and in the agricultural field.
In the automotive field, trucks and automobiles accumulate grease and dirt, particularly on the engine, where a thick oil-laden covering accumulates. This material is removed by discharging a jet of steam, sometimes mixed with detergent, onto it from a steam cleaning machine. The presently used steam cleaning machines have a number of deficiencies, so that they are often not satisfactory. In the agricultural field, animal pens have been cleaned by water under pressure.
Steam generators, for use in steam cleaning operations in the automotive field, such as in filling stations and garages, were typically provided with a source of heat, such as a kerosene burner, supplied from a kerosene tank. The exhaust gases from the kerosene burner were driven, sometimes by a blower, through a water-coil. Water was fed to the water coil either from a connection to a water main, or from a water tank, being driven by a pump. Into the conduit from the water pump to the water coil, a connection was made to a detergent tank, so that there was supplied to the water coil either water, or water and detergent. The outlet of the steam coil was connected to a hand-held nozzle construction, so as to direct the steam. This equipment required, in a typical example, a pair of electric motors, one to drive the water pump, and a second to drive the kerosene pump, and, optionally, a blower for the kerosene burner. These electric motors were powered from a typical 110 volt supply source, to which the apparatus was connected by an extension cord.
The above described apparatus was expensive, unreliable, and dangerous. Because of the number of components, it was expensive to build such machines and to market them. The machines themselves were subject to non-functioning, due in part to the fact that they had moving parts such as pumps and motors, and due in part to the fact that after a period of use, particularly in areas where the water had a high mineral content, deposits within the conduits tended to restrict and/or block the flow through the conduits. Further, such machines were often moved about a shop, such as an automotive repair shop, where the extension cord sometimes lay on a floor where water was present; if, after a period of use the extension cord insulation became worn, exposure of the electric conductor wires resulted, and these if in contact with water on the floor of the shop, could cause dangerous electrical shock to personnel, and could also create a fire. In addition, the steam cleaners of the above type required a long start-up period, perhaps five minutes from a cold start, and were unduly heavy, weighing approximately 300-400 pounds.
Other constructions of steam generator systems for use as steam cleaners in the automotive field have been suggested. For example, Murphy, U.S. Pat. No. 3,477,645 discloses such an apparatus in which a central chamber is provided for receiving a pyrotechnic cartridge, such as a road fare. The combustion chamber is surrounded by a jacket, and a connection is provided to introduce water into the jacket, where the water is heated into steam, an exhaust pipe from the chamber for the flare being located concentrically within a steam discharge pipe. This construction could only be used for a short period of time, before a flare had to be replaced, required clean out of residue from the combustion chamber, required the insertion of a burning flare into the unit, with some attendent danger, had no provision for the delivery of detergent, and no provision for the delivery of either an air and water mixture, for flushing, or an air mixture alone, for drying.
Another suggestion for the cleaning of engines is found in Mc Ouat, U.S. Pat. No. 2,984,419, wherein the source of energy for the system was the exhaust of an automobile or similar internal combustion engine. This provided an undue expense in operation, and apparently could not generate steam for cleaning purposes.
Various proposals have been made for the generation of fog or aerosol, these being equipments used in insect control and related agricultural purposes. For example, Congdon, U.S. Pat. No. 3,448,924 discloses a fog generating apparatus utilizing a pulse jet engine supplied from a gas tank such as propane or butane. A valve is provided which admits a fuel-air mixture into the combustion chamber intermittently. Waldron Jr., U.S. Pat. No. 3,141,615 discloses a fogger including a combustion engine with a spark plug which is intermittently fired, the engine being fed with fuel and air separately, liquid being delivered to the outside of an engine exhaust pipe, where it is vaporized to produce the fog which is conveyed outwardly by the engine exhaust. Stahl et al., U.S. Pat. No. 3,575,349 discloses a fog apparatus including a combustion chamber which is fed by liquid fuel and air from a carbuerator. The engine fires intermittently, or in pulses, and various liquid materials may be introduced into the exhaust for discharge with the exhaust. Frank, U.S. Pat. No. 2,858,162 discloses an aerosol generator wherein a pulse jet engine is utilized, with provision for introduction of liquid into the engine exhaust pipe. In all of these fog or aerosol generators, the discharge is of relatively low velocity, low pressure, and is therfore not suitable for steam cleaning purposes.
Broadly speaking, the generation of steam by so-called submerged combustion has long been known, as exemplified by Scheide, U.S. Pat. No. 140,220, Stewart, U.S. Pat. No. 2,981,250, and Brock U.S. Pat. No. 3,568,658.